Thermo-Disc and Fan/Limit Control?

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jedi_jackson

Member
Jan 9, 2018
21
Virginia
I have a Thermo Pride WC-27 wood furnace and I'm new to wood furnaces and my furnace has a thermo-disc (snap disc) and a fan/limit control wired into the thermostat. Is this a normal set-up, or should it have one or the other? The fan/limit switch seems to be the one that is turning on my blower, but I don't know if the snap disc has any purpose wired with it.
 
I think snap discs are usually just used as a safety measure in case the controller has a failure and gets stuck open. It's likely wired in series with the main power feed to the control circuitry, so as to "pull the plug" on the fan/air valves in case of an over temperature situation.